In order to artificially impregnate domestic animals, a number of devices have been designed. The most well recognized and utilized device that has been developed is an artificial insemination syringe or gun. While the words syringe and gun are often used interchangeably in the industry and within this application, the word syringe is believed to be technically broader in scope.
A number of different configurations for guns or syringes of this type have been developed, such as those disclosed in U.S. Pat. Nos. 4,173,227, 4,261,361, 4,846,785 and 4,865,589, which are hereby incorporated by reference in their entirety. The syringe comprises a tubular body adapted to receive a container holding the biological material to be injected into the animal. The body and container can be inserted into the animal and the material is expelled from the container by a push-rod or plunger slidably insertable into the body and the container. To enable the syringe to be used repeatedly without becoming contaminated by a particular animal, a flexible sheath can be removably positioned around the body to prevent contact of the internal fluids of the animal with the body of the gun, allowing the syringe to be reused a number of times. After each use, the sheath can be removed from around the body of the syringe and discarded, allowing a new, sterile sheath to be placed around the syringe.
When injecting material from this type of syringe in order to, for example, artificially inseminate a domestic animal, the material is normally contained within a plastic straw, such as that disclosed in U.S. Pat. Nos. 4,478,261 and 5,190,880 which are incorporated by reference herein. The straw is generally a plastic tubular structure that is sealed at one end by a pair of plugs and sealed at the other end with ultrasound. These seals retain the material within the straw. To use the straw, the ultrasound sealed end is first severed from the remainder of the straw. The end of the straw containing the plug pair is then inserted into and engaged by the body of the syringe. The straw is held in this position by the sheath placed around the body. When properly positioned, the plunger is inserted into the body and into the straw such that the plug is contacted and urged along the length of straw by the plunger to expel the material from within the straw out the opposite end.
The straws come mainly in two sizes, a smaller diameter straw having a volume of approximately one quarter cubic centimeter (¼ cc), and a larger diameter straw having a volume of approximately one half cubic centimeter (½ cc). Thus, in order to effectively discharge the material from within a particular diameter straw, the gun or syringe must be compatible with the diameter of the straw in which the material is contained. Thus, due to the different sizes of the straws available, on many occasions it is necessary for an individual conducting such procedures to change the type of syringe being used in order to accommodate the size of the straw containing the biological material to be injected. This is undesirable as it is inconvenient to constantly switch between syringes when utilizing straws of different sizes. Furthermore, based on the small differences in the sizes of the different types of straws and between the configuration of the various syringes, it may often be the case that an individual inadvertently uses a syringe with a straw that is not compatible with the syringe, thereby wasting the valuable biological material contained within the straw.
Therefore, to overcome this deficiency, an injecting syringe was developed that was capable of accommodating straws of multiple sizes. This syringe is disclosed in U.S. Pat. No. 4,173,227 and includes a tubular body defining an internal, axial cavity separated into two halves having a different diameters by a tubular insert positioned within the body. Each half is capable of receiving and retaining a straw having a specific diameter, such that the injecting syringe can utilize the straws having each of these diameters.
However, to change the configuration of this syringe to accommodate a straw having one of the two compatible diameters, the syringe must be partially disassembled in order to reverse the configuration of the body, thereby switching the ejection or outlet end of the body from one end to the other. By having to disassemble and reverse the configuration of the syringe, it is often the case that leaks occur between the reassembled elements of the syringe, such that some or all of the biological material that was to be injected is lost before it can be used. Moreover, having to repeatedly turn the syringe around is a nuisance when in a hurry.
Therefore, it is desirable to develop an injecting syringe that is capable of accommodating straws having different diameters that does not require disassembling and/or altering the syringe to prevent the material from leaking out of the syringe.